Gas lift plunger



May 4, 1965 W. L. CLINGMAN GAS LIFT PLUNGER Filed Sept. 3, 1963 United States Patent O 3,181,470 GAS LIFT PLUNGER Walter L. Clingman, 2013 Andover Court, Oklahoma City, Okla. Filed Sept. 3, 1963, Ser. No. 306,167 7 Claims. (ci. 10s-s2) This application relates generally to improved apparatus useful in the production of oil from oil and gas wells or the like. More particularly, it relates to an improved free gas lift plunger useful in the production of oil from oil or gas wells or the like wherein a gas lift operation is required.

Sometimes there is insuliicient formation gas pressure to continually drive oil from a subterranean formation to the surface. Under such circumstances, one production procedure utilized is to intermittently close the well in, that is, completely seal it off, until sufficient pressure has accumulated to drive the oil to the surface. When such pressure has accumulated, the production tubing is opened and a slug of oil will flow to the surface. Obviously, in the instance of slow gas build-up, this method of production is very slow. This method is also very inetlicient in that much of the gas commingles with the oil and is produced with it, thus reducing the quantity of oil produced as well as requiring a separator to remove the gas from the oil.

It sometimes happens that there is sutlicient formation pressure available to drive the oil from the formation into the Well, but not enough to lift the oil to the surface. Various methods have been utilized to perform the operation of moving the oil to the surface. @ne obvious and well known method is to mechanically pump the oil. This usually involves the use of a surface-mounted walking beam mechanism with sucker rods extending from one end thereof to a pump located below the oil level in the well. Also, some means must be provided to actuate the walking beam mechanism.

Another method devised to lift the oil to the surface involves the provision of an auxiliary source of gas under pressure. The gas is introduced into the annulus of the well at the surface, and when it reaches the oil, the oil is driven upwardly through the production tubing. As was true with the production by formation gas, the auxiliary gas also mixes with the oilreducing production etliciency and requiring separation. Occasionally, the gas apparently channels through the oil without lifting the oil to the surface. This occurs both in formation gas production and in the auxiliary gas production methods.

The foregoing problems have led to the development of a production tool known as a pig, traveling valve, or a plunger, but which will be referred to herein as a gas lift plunger or simply as a plunger. t is to this tool that the instant invention appertains. Gas lift plungers are used to prevent the channeling of gas through the Ioil. To a great extent they also prevent commingling of the gas and oil, thus reducing the amount of gas and oil separation required at the surface. A natural result of the better division of gas and oil is higher efficiency of production.

ln either the formation gas lift or the auxiliary gas lift method of production, the plunger is utilized in approximately the same manner. The plunger is introduced into the production tubing and the well closed in. The Well, being closed in, reaches a more or less equalized condition and the plunger falls through the oil in the tubing to the bottom of the tubing where its movement is arrested by a stopping device. The Well is allowed time to accumulate gas pressure and then opened to production. Upon opening the well, `the gas that has been isolated below the plunger drives the plunger and oil thereabove to the surface. When the plunger reaches the surface, the procedure is repeated. The quantity and speed of production in either method will depend completely upon the time required for the gas pressure to build up and/or the time required for the plunger to reach the bottom of the tubing.

In the past, gas lift plungers have generally included some type of sliding valve mechanism and one or more sealing elements positioned on a relatively short hollow mandrel. The sealing elements are generally formed of an elastic material and are of such size as to engage the walls of the production tubing. Such elements are usually shaped somewhat similar to swab cups and may include a multiplicity of thin rings that are in actual engagement with the tubing.

Several problems are encountered in the use of tools such as those described above. For example, the sealing elements are subjected to considerable stresses as they move up and down through thousands of feet of tubing and are in need of frequent replacement. Also, the friction existing between the sealing elements and the tubing wall will require more power to move the plunger, thus reducing the eiciency of production further. Most plungers include springs or other valve operating elements that are subject to corrosion and damage. Some of these valves include rather intricate mechanisms that are Subject to malfunction or damage, particularly by sand or other foreign matter carried in the oil and gas.

It is therefore one object of this invention to provide an improved gas lift plunger that is very simple in construction and extremely economical to manufacture.

Another object of this invention is to provide an improved gas lift plunger that includes a very simple, but effective, by-pass valve that is resistant to wear or damage.

An additional object of this invention is to provide an improved gas lift plunger that includes a sealing element that edectively separates the oil and gas but is highly resistant to Wear or damage.

The foregoing objects are attained by a gas lift plunger, constructed in accordance with this invention, which includes an elongated mandrel having an axial bore extending partially therethrough, ports extending through the Wall of said mandrel into the bore, a guide member slidingly mounted on the mandrel, and a sealing element slidingly mounted on the mandrel which is adapted to alternately cover `and uncover the ports therein.

Other, further, and additional objects and advantages of the invention will become more apparent as the following description is read in conjunction with the aecompanying drawing wherein like reference characters denote like parts in all views and wherein:

FIGURE l is an elevation view, partly in cross-section, of a gas lift plunger, constructed in accordance with the invention, and a section of production tubing, illustrating the various parts of the plunger in the positions they occupy as the plunger moves downwardly through the tubing;

FIGURE 2 is a View similar to FGURE 1, but illustrating the various parts of the plunger in the positions that they occupy during movement of the plunger upwardly through the tubing; and

FIGURE 3 is a cross-sectional view taken along the line 3 3 of FIGURE l.

Referring now to the drawings and to FIGURE l in particular, shown therein is a gas lift plunger generally designated by reference character within a section of production tubing 12. The tubing 12, in actual use, would be positioned within a well which is generally lined with a casing (not shown), thus forming an annulus between the exterior of the tubing 12 and the interior of the casing.

The gas lift plunger 10 includes a mandrel 14 which is preferably but not necessarily constructed from steel. The mandrel 14 has a fishing neck 16 formed or welded to its upper end 17. Spaced downwardly from Vthe fishing neck 16 is a flange 18 providing a downwardly facing shoulder 20 on its lower surface to form a stop as will be described.

An axial passageway or bore 22 is formed in the lower end portion of the mandrel 14 and extends therein approximately half the length of the mandrel 14. A plurality of ports 24 extend through the side wall 26 of the mandrel 14 into the upper end of the bore 22. For ease in manufacturing and assembly, the lowermost end portion 27 of the mandrel 14 has an exterior or male thread V28 formed thereon. A nut 30 is shown as screwed onto the threads 28 and secured thereto by means of a pin 32.

An upper guide member 34 is slidingly positioned on the mandrel 14. The guide member 34 is tubular in shape; having a longitudinal bore 35 extending therethrough. Guide member 34 has an outside diameter slightly less (such as 1A@ inch) than the inside diameter of the tubing 12 in which the plunger 10 operates. It is preferably constructed of a rather hard plastic or of 'aluminum so that it is light in weight but will have good wear characteristics. It is illustrated in FIGURE 3 as having three longitudinal grooves 36 in its exterior surface. While three grooves 36 are shown spaced approximately 120 apart, the exact shape, number, and spacing of the grooves is unimportant so long as adequate fluid passageway area is provided. The bore 35 is dimensionally controlled so that the guide member 34 is free to slide along the mandrel 14. The extent of its upward movement is limited by the downwardly facing shoulder 20 of the iiange 18.

A spacer member 38 is slidingly positioned on the mandrel V14 just below the guide member 34. Member 38 is illustrated as having a hexagonal periphery, but the exact configuration is a matter of choice. It should have an outside dimension less than the depth of the longitudinal grooves 36 in the member 34 so that it can not interfere with the flow of fluid from the ports 24 through the grooves 36 as will be described. Spacer member 38 is constructed from a relatively heavy material, such as brass or steel, for reasons that will become apparent as the description proceeds.

Slidingly positioned on the mandrel 14 below the spacer member 38 is a sealing member 40. The member 40 is generally tubular in shape and has a plurality of circumferential grooves 42 formed in the outside diameter thereof. A hard light-weight plastic is preferably used to make the member 40, but aluminum or other materials that are light in weight but exhibiting good wear characteristics may be used if desired. The outside diameter of the sealing member is slightly less than the inside diameter of the tubing 1 2 in which the plunger 10 is to be used. A plunger 10 with a sealing member 40 having anoutside diameter one sixteenth of an inch less than'the inside diameter of the tubing 12 has been run in wells and proved to be entirely satisfactory. This is not meant to limit the invention to a specific dimension, but to serve only as an example of the comparative dimensions of one working plunger. Below the sealing member 4t) and also positioned'on the mandrel 14 is a washer 44 that serves to prevent damage to the lower end of the sealing member 40. Y

4 Operation The gas lift plunger 10 is placed in the production tubing 12 at the surface of the well. If there is some pressure on the well, it is closed in to allow pressures above .and below the plunger 1li to equalize. If there is no pressure, the plunger 10 will begin to fall through the tubing 12. As it travels downwardly, the various parts of the plunger 10 assume the positions illustrated in FIGURE l. The washer 44 is resting on thenut 30 with the sealing member 40 resting on the washer 44, and the spacer member 38 resting on the sealing member 40. The spacer member 38 is of suiiicient weight to force the sealing member 40 and washer 44 against the nut 30 once the pressures in the well have balanced. As the plunger 10 moves downwardly, fluid thereinbelow passes through the bore 22 and out the ports 24, thence through the longitudinal grooves 36 of the guide member 34. With the ports 24 open, the plunger 10 will fall away very rapidly. It is important to note that it will fall even though the ports 24 should become plugged or should the guide member 34 or sealing member 40 become lodged over the ports 24. The plunger 10 will fall with the ports 24 closedV because the sealing member 40 is not in contact with the inside of the tubing 12, thus the fluid can flow around the circumference of the plunger 10. It will not fall as rapidly, but it will fall, thus preventing one possibility of malfunction. y

Upon reaching the stopping device (not shown) near the bottom of the tubing 12, the guide member 34 will slide'down the mandrel 14 covering the ports 24, thereby isolating the oil and gas below the plunger 10 from the oil thereabove. The well is kept closed in and the formation gas pressure allowed to build up or an auxiliary gas is introduced into the annulus.V

When sufficient pressure has accumulated to lift the head of oil above the plunger 10, the guide member 34, spacer member 38, sealing member 40 and washer 44 will move upwardly on the mandrel 10 until the upper end of the guide member 34 rests against the downwardly facing shoulder 20 of the flange 18. During the movement of the members as just described, the ports 24 remain closed at all times. This is the position of the various parts as illustrated in FIGURE 2 andas the plunger 10 is driven upwardly through the tubing 12 by the gas pressure. Upon reaching the surface, the cycle is repeated to produce additional slugs of oil. Y

While some gas may bypass the plunger 10 by moving between the outside diameter of the sealing member 40 and the inside diameter of the tubing 12, it has been proved in actual field operations that the plunger 10 works effectively to separate the oil and gas. The exact theory upon which the seal takes place is not completely understood, but it is believed that the closeness between the outside diameter of the sealing member 34 and the inside diameter of the tubing coupled with the inherent surface tension of the oil film therebetween cooperates to form an effective seal.

It should be apparent from the foregoing that apparatus constructed in accordance with this invention provides a novel gas lift plunger that forms an effective seal with the tubing in which itV operates, thereby separating or dividingthe oil to be produced from the gas used to produce it. It should be obvious that less friction will be required to move the gas lift plunger through the tubing because of the clearance between the plunger and tubing, thereby increasing the efliciency of production by lowering the pressure requirements for moving the plunger. As previously pointed out, the possibility of a malfunction dueto failure of the valve mechanism is reduced to a minimum due to the ability of the plunger to fall even though the ports may be plugged The above description is by way of example only and it should be understood that many modiiications and variations may be made thereto without departing from the i spirit of the invention or from the scope of the annexed claims.

I claim:

l. A gas lift plunger including:

an elongated mandrel having an upper end and a lower end and having a tiange near the upper end thereof forming a downwardly facing shoulder,

means forming an axial bore extending partially through said mandrel from the lower end of said mandrel, and

means forming at least one port extending trans- Versely through the medial portion of said mandrel into said bore;

a generally tubular guide member slidingly positioned on said mandrel below said shoulder and having at least one longitudinally extending iiuid passageway formed therein;

a sealing member slidingly positioned on said mandrel below said guide member; and

retaining means iixed to said mandrel below said downwardly facing shoulder a distance greater than the combined lengths of said guide member and sealing member for retaining said guide member and sealing member on said mandrel;

the arrangement -being such that said guide member and sealing member are adapted to cover and uncover said port.

2. A gas lift plunger including:

an elongated mandrel having an upper end and a lower end and having a iishing neck on the upper end thereof, a harige near the upper end thereof forming a downwardly facing shoulder,

means forming an axial bore extending partially through said mandrel from the lower end of said mandrel,

means forming a plurality of ports extending transversely through the medial portion of said mandrel into said bore;

a generally tubular guide member slidingly positioned on said mandrel below said shoulder and having longitudinally extending iluid passageways formed therein;

a spacer member slidingly positioned on said mandrel below said guide member;

a sealing member slidingly positioned on said mandrel below said spacer member and having a plurality of circumferential grooves formed in the exterior thereof;

and retaining means fixed to said mandrel a distance below said downwardly facing shoulder greater than the combined lengths of said guide member, spacer member and sealing member for retaining said guide member, spacer member, and sealing member on said mandrel;

the arrangement being such that said guide member and sealing member are adapted to cover and uncover said ports.

3. A gas lift plunger for use in production tubing positioned in an oil and gas well or the like wherein said plunger includes:

an elongated mandrel having an upper end and a lower end and having,

a flange near the upper end thereof forming a downwardly facing shoulder,

means forming an axial bore extending partially through said mandrel from the lower end of said mandrel through said mandrel, and

means forming at least one port extending transversely through the medial portion of said mandrel into said bore;

a generally tubular guide member slidingly positioned on said mandrel below said shoulder and having at least one longitudinally extending duidl passageway formed therein;

a sealing member slidingly positioned on said mandrel below said guide member and having an outside diameter less than the inner diameter of the production tubing; and

retaining means fixed to said mandrel below said downwardly facing shoulder a distance greater than the combined lengths of said guide member and sealing member for retaining said guide member and sealing member on said mandrel;

the arrangement being such that said guide member and sealing member are adapted to cover and uncover said port.

4. A gas lift plunger for use in production tubing positioned in an oil .and gas well or the like wherein said plunger includes:

an elongated mandrel having an upper and a lower end and having,

a fishing neck on the upper end thereof, a flange near the upper end thereof forming a downwardly facing shoulder,

means forming an .axial bore extending partially through said mandrel from the lower end of said mandrel through said mandrel, and

means forming a plurality of ports extending transversely through the medial portion `of said mandrel into said bore;

a generally tubular guide member slidingly positioned on said mandrel below said shoulder and having longitudinally extending tluid passageways formed therein;

a spacer member slidably positioned on said mandrel below said guide member;

a sealing member slidingly positioned on said mandrel below said spacer member and having a plurality of circumferential grooves formed in the exterior thereof;

said sealing member having an outside diameter less than the inner diameter of the production tubing; and

retaining means fixed to said mandrel a distance below said downwardly facing shoulder greater than the combined lengths of said guide member, spacer member and sealing member for retaining said guide member, spacer member, and sealing member on said mandrel;

the arrangement being such that said guide member and sealing member are adapted to cover and uncover said ports.

5. In apparatus for use in producing oil from oil and gas wells, or the like, said apparatus including production tubing positioned with the well;

a gas lift plunger operably positioned within said production tubing and including an elongated mandrel having an upper end and lower end and having a flange near the upper end thereof forming a downwardly facing shoulder,

means forming an axial bore extending partially through said mandrel from the lower end of said mandrel, and

means forming at least one port extending transversely through the medial portion of said mandrel into said bore,

a generally tubular guide member slidingly positioned on said mandrel below said shoulder and having at least one longitudinally extending iiuid passageway formed therein,

a sealing member slidingly positioned on said mandrel below said guide member and having an outside diameter less than the inside diameter of said production tubing, and

retaining means iixed to said mandrel below said downwardly facing shoulder a distance greater than the combined lengths of said guide mem- 7 ber and sealing member for retaining said guide 7. The gas life plunger of claim 1 wherein said sealmember and, sealing member on said mandrel, ing member is constructed of Va relatively light-weight, Vthe arrangement being such that said guide memsubstantially rigid metal.

ber and sealing member are adapted Vto cover Y and uncover Said port Y 5 Y No references cited.

6. The gas lift plunger of claim 1 wherein said sealf ing member is constructed of a relatively light-Weight, LAURENCE V' EFNER Primary Examiner' substantially rigid plastic. WARREN COLEMAN, VExamz's'fzer 

1. A GAS LIFT PLUNGER INCLUDING: AN ELONGATED MANDREL HAVING AN UPPER END AND A LOWER END AND HAVING A FLANGE NEAR THE UPPER END THEREOF FORMING A DOWNWARDLY FACING SHOULDER, MEANS FORMING AN AXIAL BORE EXTENDING PARTIALLY THROUGH SAID MANDREL FROM THE LOWER END OF SAID MANDREL, AND MEANS FORMING AT LEAST ONE PORT EXTENDING TRANSVERSELY THROUGH THE MEDIAL PORTION OF SAID MANDREL INTO SAID BORE; A GENERALLY TUBULAR GUIDE MEMBER SLIDINGLY POSITIONED ON SAID MANDREL BELOW SAID SHOULDER AND HAVING AT LEAST ONE LONGITUDINALLY EXTENDING FLUID PASSAGEWAY FORMED THEREIN; A SEALING MEMBER SLIDINGLY POSITIONED ON SAID MANDREL BELOW SAID GUIDE MEMBER; AND RETAINING MEANS FIXED TO SAID MANDREL BELOW SAID DOWNWARDLY FACING SHOULDER A DISTANCE GREATER THAN THE COMBINED LENGTHS OF SAID GUIDE MEMBER AND SEALING MEMBER FOR RETAINING SAID GUIDE MEMBER AND SEALING MEMBER ON SAID MANDREL; THE ARRANGEMENT BEING SUCH THAT SAID GUIDE MEMBER AND SEALING MEMBER ARE ADAPTED TO COVER AND UNCOVER SAID PORT. 